(1) Field of the Invention
The present invention relates to a film-shaped encapsulating agent for electronic parts, more particularly to a film-shaped encapsulating agent for electronic parts which enables the continuous encapsulation of electronic parts without requiring any expensive apparatus because of good processability (therefore, no cost increase is incurred) and is excellent in heat resistance and electrical insulation after the encapsulation.
(2) Description of the Prior Art
In general, various electronic parts are often encapsulated with various materials at the final production step in order to avoid the bad influence of moisture, dust and the like in air. Such encapsulation of electronic parts have heretofore been carried out, for example, by encapsulation with a thermosetting resin by transfer molding, or by placing an electronic part in a box-shaped pot, and then pouring a resin into the pot to encapsulate the part (potting method), or by using, as an encapsulating agent, a film obtained by coating a substrate such as cellulose or the like with a B-stage resin (for example, epoxy resin).
However, in the encapsulation with a thermosetting resin by transfer molding, a high cost is incurred because an expensive transfer-molding machine and an expensive mold must be used. In the potting method, continuous operation is difficult and hence the number of operational steps is large, the maintenance of quality is hence difficult and, in addition, the preparation of a pot is necessary; therefore, a high cost is incurred. In the method using a film obtained by coating the above-mentioned substrate with a B-stage resin, the film has a short life because the resin is in the B-stage and, moreover, the maintenance of quality is difficult.